1. Field of the Invention
The present invention relates to an electrical connector for a flat circuit device, such as a flexible printed circuit board (hereinafter, referred to as an FPC), a flexible flat cable assembly (hereinafter, referred to as an FFC) or the like, and more particularly to an improvement in an electrical connector with which contacting terminals provided on a flat circuit device are put in engagement with a mating electrical connector mounted on a main circuit board, such as a solid printed circuit board, to be connect electrically with the same.
2. Description of the Prior Art
A relatively small-sized flat circuit device, such as a relatively small-sized FPC or FFC, used in various kinds of electronic apparatus is often connected electrically with a solid printed circuit board, on which various electrical parts are directly mounted, through an electrical connector which is fixed to and connected electrically with the solid printed circuit board.
For connecting the relatively small-sized flat circuit device electrically with the solid printed circuit board, there has been previously proposed to provide the flat circuit device with a connectively engaging protrusion on which a plurality of contacting terminals are arranged and to put the connectively engaging protrusion of the flat circuit device in electrical engagement with the electrical connector which is fixed to and connected electrically with the solid printed circuit board so that the flat circuit device is electrically connected with the solid printed circuit board through the electrical connector.
In such a previous proposal, a plug type electrical connector is substantially constituted on an end portion of the flat circuit device so as to include the connectively engaging protrusion of the flat circuit device and the plug type electrical connector thus constituted is put in engagement with the electrical connector fixed to and connected electrically with the solid printed circuit board, which functions as a receptacle type electrical connector, as disclosed in, for example, each of Japanese patent applications published before examination under publication numbers 2006-173051 and 2009-266749 (hereinafter, referred to as published patent documents 1 and 2, respectively).
In a previously proposed plug type electrical connector (a connector (101)/(102)/(103)) disclosed in the published patent document 1, an end portion of a flat circuit device (an FFC (50)) is put between a pair of insulated housings (a base insulator (10) and a cover insulator (20)) so that a connectively engaging protrusion at a front end of the flat circuit device, on which a plurality of contacting terminals (conductors (52)) are arranged, is placed to project to the outside of the insulated housings and a pair of conductive shells (a shell (30) and a cover shell (40)) are provided to cover respectively the insulated housings from the outside thereof. The connectively engaging protrusion of the flat circuit device is held by the insulated housings which are opposite to each other with the connectively engaging protrusion between and put between the conductive shells. Then, when the connectively engaging protrusion of the flat circuit device is put in electrical engagement with a connectively engaging opening provided on a receptacle type electrical connector (a mating electrical connector), the contacting terminals arranged on the conductively engaging portion of the flat circuit device are electrically connected with contacts (mating contacts (81)) provided in the receptacle type electrical connector.
Further, in another previously proposed plug type electrical connector (a plug connector (1)) disclosed in the published patent document 2, an end portion of a flat circuit device (a signal transmitting medium (2)) forming a conductively engaging portion on which a plurality of contacting terminals (conductors (21)) are arranged is inserted into an insulated housing (12) through an opening path (12a) provided therein to be fixed to the insulated housing (12) with the conductively engaging portion projecting to the outside of the insulated housing (12) and the insulated housing (12) is put between a pair of conductive shells (a first conductive shell (13a) and a second conductive shell (13b)) opposite to each other. The connectively engaging protrusion of the flat circuit device is held by the insulated housing (12) which is put between the conductive shells opposite to each other and in which the opening path through which the end portion of the flat circuit device forming the conductively engaging portion is inserted in the insulated housing (12) is provided. Then, when the connectively engaging protrusion of the flat circuit device is put in electrical engagement with a connectively engaging opening provided on a receptacle type electrical connector (a mating electrical connector), the contacting terminals arranged on the conductively engaging portion of the flat circuit device are electrically connected with contacts provided in the receptacle type electrical connector.
With each of the previously proposed plug type electrical connectors thus constituted to include the connectively engaging protrusion of the flat circuit device, the connectively engaging protrusion of the flat circuit device is directly engaged with the connectively engaging opening provided in the receptacle type electrical connector so that the contacting terminals arranged on the conductively engaging portion of the flat circuit device come into contact respectively with the contacts provided in the receptacle type electrical connector to be electrically connected through the receptacle type electrical connector with the solid printed circuit board to which the receptacle type electrical connector is fixed.
The previously proposed plug type electrical connector which is constituted to include the connectively engaging protrusion of the flat circuit device, as disclosed in the published patent document 1 or 2, comprises the insulated housings opposite to each other with the end portion of the flat circuit device between or the insulated housing provided therein with the opening path through which the end portion of the flat circuit device is inserted into the insulated housing as a main structural element thereof. Accordingly, in the plug type electrical connector thus proposed previously, at least, there have been disadvantages that a size in a direction of the thickness of the flat circuit device is increased, the constitutive parts are increased in number, the assembling steps and time are increased, the production cost is increased and so on. Further, in the plug type electrical connector thus proposed previously, there has been an additional problem that, since various structural members or parts are positioned with reference to the insulated housing, the insulated housing is required to be processed with extremely high precision.
Besides, in the previously proposed plug type electrical connector disclosed in the published patent document 2, a grounding path from a shielding conductor provided on the flat circuit device through the conductive shell to a ground connecting portion of the receptacle type electrical connector is made relatively long so that variations in distance between the grounding path and each of the contacting terminals arranged on the connectively engaging protrusion of the flat circuit device are brought about. Therefore, it is feared that each of the contacting terminals through which signals are transmitted is varied in its characteristic impedance so that impedance-mismatching is brought about on each of the contacting terminals.